Iieinrich c



nrrnn TATES HEINRICH C. ASCHERMANN, OF CASSEL, GERMANY.

PROCESS OF EXTRACTING METALS FROM METALLIC OXIDS.

SPECIFICATION forming part of Letters Patent No. 610,014, dated August30, 1898..

Application filed April 20, 1897. Serial No. 633,061.

(No specimens.) Patented in Germany June 30, 1896, No. 93,744, and

N vem r 24,1896,No.94,405; in England January 12,1897, No. 859, inBelgium January 30, 1897,No.125,5 98, and

in France April 20,1897, No. 262,994.

To atZZ whom it may concern:

Be it known that I, HEINRICH O. ASCHEE- MANN, a subject of the GermanEmperor, residing at Gassel, Germany, have invented certain new anduseful Improvements in Extracting Metallic Alloys and Pure Metals byElectric Heat, (patented in Germany November 24, 1896, No. 94,405, andJune 30, 1896, No. 93,744; in France April 20, 1897, No. 262,994; inBelgium January 30, 1897, No. 125,506, and in Great Britain January 12,1897, No. 859;) and I do hereby declare that the following is a full,clear, and exact description of the invention, which will enable othersskilled in the art to which it appertains to use the same.

In electric furnaces the extraction of pure metals from their oxidspresents considerable difficulties when the metals have great affinityfor carbon. There results in that case a carburet or a metal containinga large proportion of carbon, and it becomes necessary, in consequence,to add a very fusible metal as a flux, which combines with the reducedmetal in the nascent state and prevents it, accordingly, from absorbingcarbon 5 but that alone is not sufficient. In order to obtain a metal asnearly as possible free from carbon, it is essential that the reductionshould be effected rapidly and that it should be produced by the weakestpossible currents. That is indispensable, even when no regard is paid tothe question of economy. lhave never succeeded in obtaining the metalreduced to a state of purity by the prolonged action of the .voltaic areor by the use of more intense currents. The flux volatilizes and isimmediately replaced by the carbon of the elec trodes. The reducedmetalbecomes saturated with carbon proportionately to the volatilizationof the flux. The flux has little or no in fluence on the course of thereduction. serves simply to prevent the entry of carbon into thecombination. If, however, a metallic sulfid is taken as a flux, thereduction is effected more rapidly and with less expenditure ofthermo-electric energy. It will be seen that it is the sulfur whichfavors the reaction.

If it is desired to obtain a pure metal, the

I sulfid of a very fusible metal is taken as a flux,which can easily bevolatilized and driven off from the resulting alloy by reheating.Experiments have shown that the best results are obtainable by the useof sulfid of anti mony, (Sb S The mixture of the metallic oxid with themetallic sulfid is produced in simple atomicproportions, the sulfid, however, being slightly in excess. The mixture is interposed in the circuitof an electrical fusion-furnace. The mixture to be reduced forms thenegative pole of the are, because the greatest heat is there developed.A carbon stick or bar may be inserted in the mixture and the positivewire connected with it, while the negative wire will be attached to thebase of the furnace. The current employed may have the proportion ofseven amperes to one volt or multiples of the samethus, fourteen amperesto two volts or twentyeight to four. If large quantities are to bemelted, even three hundred and fifty amperes may be required, but fiftyvolts will not be. The voltage should be kept as low as possible. By wayof example: To extract metallic chromium, chromium oxid and sulfid ofantimony are mixed in the proportion of ten to twenty-three. Theantimony is driven from the resulting alloy by reheating, and whatremains is pure chromium. The reaction may be theoretically expressed asfollows:

This, however, is only correct so far as the formation of an indefinitequantity of alloy of the chromium and antimony is concerned, withantimony in excess, for in the upper part of the furnace in which theoperation is carried on there may be deposited some crystals of the oxidof antimony, the sulfid of antimony, and chromic oxid, which wouldgreatly modify the above reaction. It is sufficient to know, however,that an alloy of relatively pure chromium and antimony will be formed asa residuum in the lower part of the furnace, and that the more volatileof these elements (the antimony) may be driven off by subsequentheating. For the oxid of alu minium the proportion is ten forthirty-seven of sulfid of antimony. The mixture, being ICQ I claim, anddesire to secure by Letters Pat ent, is-

The process of extracting metals from metallic oxids, which consists inadding to such oxids the sulfid of antimony in greater proportion thanthe oXid, and then subjecting the mixture to electric currents, asspecified.

HEINRICH C. ASCHERMANN. [L. s]

Witnesses:

HERMANN MENcHE, HERMANN AREND.

